Monitor display has become pale

Try the reset button, a different cable if possible, make sure the cables are firmly connected to the monitor and video card.  Try another video card driver, after making sure the video card is well seated.  Some times they can become loose from the slot.  Try another computer as well.  If nothing works from my suggestions, and the User Guide linked below, the monitor might be going bad.  Are you still under warranty  ?  Monitor was introduced in 2005, and most Dell monitors have a 3 year warranty.

http://support.dell.com/support/edocs/monitors/M993s/en/index.htm   993s User Guide